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the first report of its use in a patient with insulin unresponsiveness.We do not know why our patient was unresponsive or how

plasmapheresis worked. Our patient had an excellent response tocentral venous infusions for 8 months, which argues against insulinreceptor antibodies as the cause. However, we are developing asystem for selective removal of anti-insulin antibodies by affinitycolumn adsorption. In vitro we selectively removed 85% of thispatient’s anti-insulin IgG antibodies on a single pass through anaffinity adsorption column. Selective removal of her anti-insulinantibodies would represent a more satisfactory form of treatmentand would directly identify the cause of her insulin problem.

School of Paediatricsand Centre for Biomedical Engineering,

University of New South Wales,Kensington, NSW 2033, Australia,and Prince of Wales Children’s Hospital,

Randwick, NSW

GABRIEL ANTONYVASILIOS A. BERDOUKASBRETT CHARLTONSTEPHEN G. COOPERNURSEN GURTÜNCAWILLIAM H. KELLY

SENSITIVE, RAPID, SIMPLE METHODS FORDETECTING CRYPTOSPORIDIUM IN FAECES

SIR,-The protozoon CrvDtosporidizim is an established cause ofhuman gastroenteritis, , and Giemsa and Ziehl-Neelsen

techniques are recommended for the detection of oocysts in

faeces. ,3-5 We have used these methods to diagnosecryptosporidiosis in two patients and a nurse in a children’s

hospital,6 and, more recently, in six other patients and two siblingcontacts.

Although these methods are generally effective we felt there wasroom for improvement. Both methods are slow and require carefuldecolorisation. Colour contrast with Giemsa is poor and requires oilimmersion microscopy. With Ziehl-Neelsen it is excellent.However, there is important evidence, which we can confirm, thatoocysts do not always stain with carbol-fuchsin. Some patientsexcrete few oocysts, and cases may be missed if a sensitive method isnot used.Here we describe staining methods which are sensitive, simple,

and rapid and which have sufficient colour contrast to permitscreening at low magnification. Aqueous dilutions of stains weremade from commercially available liquid concentrates (ParamountReagents, Liverpool). Smears were fixed and stained as describedbelow, quickly dried, and examined after a coverslip had beenmounted in ’DPX’ mountant (BDH).Excellent results were obtained using 1% safranin for 1 min as

primary stain. Heating until steam appeared was necessary for thebest results; excess heat was not deleterious. Oocysts stained abright orange, usually within a clear halo. They were doughnut orcrescent shaped with a lighter staining centre. Fixation with 3%HCI in methanol (acid-methanol) for 3-5 min gave the best results.Although full heat fixation before acid-methanol treatment was lesssatisfactory, a single pass through the flame of a bunsen burnerhelped to secure oocysts to the slide. Methylene-blue (107o for 30 s)was the best counterstain; crystal-violet (0 - 107o, 30 s) was almost asgood but malachite-green was unsatisfactory.Good results were also obtained with 1% methylene-blue, again

heating for 1 min. Acid-methanol fixation was necessary but could

1 Jokipii L, Pohjola S, Jokipii AMM. Cryptosporidium: a frequent finding in patientswith gastrointestinal symptoms Lancet 1983; ii: 358-61

2 Casemore DP, Jackson B. Sporadic crypospondiosis in children. Lancet 1983; ii: 679.3 Garcia LS, Bruckner DA, Brewer TC, Shimuzu RY Techniques for the recovery and

identification of Cryprosporidium oocysts from stool specimens J Clin Microbiol1983; 18: 185-90.

4 Tzipon S, Angus KW, Gray EW, Campbell I. Vomiting and diarrhea associated withcryptosporidial infection. N Engl J Med 1980; 303: 818.

5 Henriksen SA, Pohlenz JFL. Staining of cryptosporidia by a modified Ziehl-Neelsentechnique. Acta Vet Scand 1981; 22: 594-96

6 Baxby D, Hart CA, Taylor C. Human cryptosporidiosis: a possible case of hospitalcross infection. Br Med J (in press)

7 Miller RA, Holmberg RE, Clausen CR. Life-threatening diarrhea caused bycryptosporidium in a child undergoing therapy for acute lymphocytic leukemia. JPediatr 1983; 103: 256-59

be used after heat fixation. Oocysts, which had the morphologydescribed above, were bright blue. Basic fuchsin (0’ 05% for 30 s)was the best counterstain.Neither of these methods require separate decolorisation and both

can be done quickly (in less than 2 min) and easily. Choice ofprimary stain and, with safranin, counterstain should be madeindividually; we prefer safranin/methylene-blue.As with the Ziehl-Neelsen method faecal debris and some yeasts

occasionally take up the primary stains. Yeasts are smaller thanoocysts, stain evenly with primary stain, have a thick rim ofcounterstain and no clear halo. Smears may be screened routinely atx 200, and possible oocysts checked at x 400; oil immersion is notnecessary.Both methods stained all the oocysts in fresh material and

60-80% in samples 5.months old. We can confirm that the Ziehl-Neelsen method sometimes stains only a small proportion ofoocysts,7 even in fresh material. This is important and we easilydiagnosed cryptosporidiosis in two patients who were negative byZiehl-Neelsen.

Increasing interest is being shown in human cryptosporidiosis butscreening of faeces is time-consuming. Published incidences 1,2based on Ziehl-Neelsen and Giemsa methods are rather low, andmore sensitive methods should detect more cases. The data

provided here offer a choice of methods which are more sensitiveand much quicker and easier than those currently used.

We thank Dr C. A. Hart for his interest and for arranging access to faecal

samples.

Department of Medical Microbiology,University of Liverpool,Royal Liverpool Hospital,Liverpool L7 8XP

DERRICK BAXBYN. BLUNDELL

CHEST X-RAYS AND CHILDHOOD ASTHMA

SIR,-Your Oct 15 editorial implied that a chest X-ray should notbe routine in acute childhood asthma, a conclusion based largely onan analysis of chest X-rays taken in an American emergency room inthe Bronx, New York.l We suggest that caution be applied beforethese findings are extrapolated to children with acute asthmaadmitted to paediatric wards in Britain. It would be a mistake forpaediatricians in the UK to accept that the chest X-ray in a childadmitted with acute asthma is not a useful investigation or that theyield from these X-rays is low.X-rays on the first 50 children admitted to a study of acute severe

asthma at this hospital have been analysed by a paediatric radiologistwho found that 16 (32%) had evidence of consolidation. 11 of these16 positive X-rays had been correctly identified by the junior staffwhen the child was admitted. Only 2 X-rays were incorrectlythought by the junior admitting doctor to show infective change.Patterns of primary care differ significantly in the UK and USA.

The American study was based on children seen in the emergencyroom, and only 26 (7’ 4%) of the 350 patients were admitted. Ofthem 8 (31%) had a positive X-ray, a figure very similar to ours.In our experience a chest X-ray is a useful adjuvant to the clinical

findings in acute childhood asthma, especially in the youngerpatient who is often more difficult to assess clinically. Indeed, theyounger the patient and the more junior the doctor, the morehelpful is the X-ray. Moreover, the interpretation of the X-ray inacute asthma and the recognition of the high yield of positivefindings form part of the young physician’s education.We would, however, endorse your editorial’s main message that

any child who is not responding rapidly to routine treatmentwarrants an immediate chest X-rav.

St James’s University Hospital,Leeds LS9 7TF

D. R. N. GILLIESS. P. CONWAY

J. M. LITTLEWOOD

1. Gershal JC, Goldman HS, Stein HS, Shelor SP, Ziprkowski. The usefulness of chestradiographs in first asthma attacks. N Eng J Med 1983; 309: 336-39.